The state of the art that is normally employed in making rollable covers for door or window openings calls for rollable covers, also referred to as rollable blinds, with connecting sections inserted between the slats that form the roll-up mechanism. These sections are designed with projections that run longitudinally over the lateral faces of the sections and are designed to wedge against the guides of the rollable cover when an attempt is made to force it open.
Thus, Spanish Utility Model U8900808 discloses a safety device for rollable doors or blinds that is characterized by the fact that the opposing edges of the connecting sections between the successive pairs of slats are covered longitudinally by extensions that are rolled up in opposite directions in order to attach them, with the option of turning, to adjacent open extensions of the respective adjacent slats. If an upward force is applied to the lower slats of the rollable cover, when an abrupt and inappropriate attempt is made to force the rollable cover open, the connecting section is caused to turn around its geometric center and wedges against the slat just above it and, at its ends, wedges at the inside surfaces of the guide channels of the cover in order to keep the blind from being opened.
Owing to the design of the slats of the blind, these devices require that the between-slats connecting section be made in the shape of a hook that is open on both sides and is thus usually designed in the general shape of an S that encompasses the extensions that are rolled up in opposite directions of the adjacent slats. In this way, the connecting section completely takes up the wedging force.